光纤共振原理的研究

对微振动进行放大的光纤共振原理进行了研究。光纤共振时，不同的光纤直径和长度对应着不同的共振频率。从理论和实验上表明，光纤的共振频率与光纤振动长度的平方成反比，这为以后该传感器的应用提供了有效的数据参考。     

Soliton-like pulse train generation using a nonlinear optical loop mirror constructed from dispersion decreasing fiber

A nonlinear optical loop mirror constructed from dispersion decreasing fiber is used to generate a high-quality pulse train from a dual frequency beat signal. Numerical simulations show that, unlike previous techniques based on adiabatic compression in dispersion decreasing fibers which limited the repetition rates to >50 GHz, the proposed method does not use adiabatic compression and can be extended to repetition rates <20 GHz using reasonable fiber lengths.     

基于光纤四波混频效应的2R全光再生方法研究

提出了一种基于光纤中四波混频(FWM)效应实现对光信号的再放大和再整形的2R再生功能的方法,分析了该方法的工作原理,设计了一种基于光纤FWM效应实现光信号2R再生的光纤传输仿真系统。仿真结果表明,2R再生信号良好,系统Q值达到21.59,验证了该方法的可行性。所设计的2R再生方案中,泵浦光的波长与功率是影响FWM效率和2R再生性能的主要因素,对其进行了扫参研究,得出泵浦波长为1 548nm、功率为40dBm时,2R再生性能最优。     

一种基于调制边带技术的光生毫米波新方法

提出了一种新型的基于调制边带技术的光生毫米波方法,它主要利用高非线性光纤的四波混频效应将中心站频率较低的信号在基站上转换到毫米波射频信号.仿真实验证明该方法可以实现将中心站3.33 GHz 的驱动频率在基站频率上转换为39.96 GHz 的毫米波载波信号.     

光纤混色技术在大屏幕激光显示中的应用研究

简要介绍了大屏幕激光显示系统的原理,并且对利用光纤混色和分光镜混色进行了分析对比,详细阐述了光纤混色过程中对光纤的选择、端面处理、耦合条件及透镜的选择,指出光纤混色技术在实际大屏幕激光显示中的应用前景。     

基于高非线性光纤中四波混频效应的全光取样系统

为了克服高比特率光信号实时取样时所面临的高速模数转换(ADC)限制,构建了一套基于高非线性光纤(HNLF)中四波混频效应的全光等效取样系统。全光取样系统主要包括取样脉冲信号产生、全光取样门和信号处理3部分,其中全光取样门为本系统的核心部分。取样脉冲和信号共同注入到HNLF中,基于四波混频效应实现全光取样。实验中,分别以10Gb/s、40Gb/s非归零OOK信号进行了取样实验验证。实验结果表明该取样系统可以实现高速光信号的取样过程。本文取样系统结构简单,且不受光信号速率的限制,可应用于更高速率的信号测量。     

A Novel Method of All‐Optical Switching: Quantum Router

Subpicosecond all‐optical switching method based on the simultaneous two‐photon coherence exchange is proposed and numerically demonstrated. The optical switching mechanism is based on the optical field induced dark resonance swapping via nondegenerate four‐wave mixing processes. For potential applications of ultrafast all‐optical switching in fiber‐optic communications, 10‐THz channel number independent quantum router is discussed.     

毫米波生成系统中估算偏振模色散引起功率损耗的新方法(英文)

提出了一种在基于光外差法毫米波生成系统中估算由偏振膜色散(PMD)引起的功率损耗的新方法。不同于之前的方法,此方法将在光纤中传输的光载波视为一个随机过程,计算出了其自相关函数,并利用帕斯瓦尔定理估算功率损耗。利用此方法估算出在单模光纤(SMF)中由PMD引起的功率损耗,计算结果与之前方法得出的结果相似,证明了此方法的正确性。最后,直观地给出60 GHz信号在3个不同传输距离下由PMD引起的功率损耗。     

Sagnac fiber interferometer with the population grating for fiber Bragg grating dynamic strain sensing

A Sagnac fiber interferometer with the population grating formed in saturable erbium-doped fiber (EDF) for fiber Bragg grating (FBG) dynamic strain sensing is proposed. In this configuration, a semiconductor optical amplifier (SOA)-based fiber ring laser with an FBG reflector is employed in the sensing part and a Sagnac interferometer based on transient two-wave mixing (TWM) via dynamic population gratings in single-mode polarization maintaining erbium-doped fiber (PM-EDF) is used in this detecting part. Experimental results show that the Sagnac fiber interferometer detection system can stably respond to dynamic strains at high frequencies. As an example of application, the response of the sensor system to continuous sinusoidal ultrasonic signals is presented. The proposed simple and robust configuration has an all-fiber design based on commercially available elements, which makes it promising for applications in fiber optic ultrasonic sensors.     

A tunable multiwavelength fiber ring laser for measuring polarization-mode dispersion in optical fibers

We describe and demonstrate a tunable triple-wavelength erbium-doped fiber ring laser along with a method of measuring polarization-mode dispersion (PMD) in optical fibers based on a broad-band orthogonal-pump four-wave mixing in a semiconductor optical amplifier. The measured PMD results for optical fibers are in good agreement with values measured by means of commercial PMD testing equipment.     

Measurement of propagation constants related to material properties in high-bandwidth optical fibers

The material contribution to group index and material dispersion were measured in high-bandwidth graded-index optical fibers. A shuttle-pulse technique provided measurements of group index with precisions and accuracies of 0.1 and 0.2 percent using 5 m lengths of optical fiber. Material dispersion in fibers was measured over the0.8-0.9 mum wavelength region using different wavelength, short-pulse laser diodes. The influence of material dispersion on fiber bandwidth measurements was evaluated for laser diode sources. Limitations arising from source linewidth were experimentally determined from measurements on a fiber with high microbending enhanced bandwidth.     

高速光通信系统中全光解复用技术

本文介绍了3种在全光时分复用(OTDM)系统中所采用的解复用器:一是基于 Sagnac干涉仪的光纤非线性光环路镜(NOLM)解复用器,二是采用行波半导体激光放大器的非线性光环路镜(TWSLA—NOLM)解复用器,三是基于频率转换的四波混频(FWM)解复用器。解复用嚣是全光信息处理中的关键技术之一。     

采用两个级联外部调制器产生四倍频光载毫米波的光纤无线通信系统

研究了一种采用两个级联外部调制器基于光载波抑制原理产生四倍频毫米波的光纤无线通信(ROF)系统.在中心站利用电混频器产生副载波复用信号,通过第一个外部调制器产生两倍射频(RF)信号的光载毫米波信号,再通过第二个外部调制器产生四倍射频信号的光载毫米波.实验显示采用频率为10 GHz的射频信号源和2.5 Gbit/s的数据基带信号混频通过两个级联外部凋制器后产生毫米波的频率为40 GHz,并且在单模光纤中传输距离达20 km,功率代价小于2 dB.     

Silica-air double-clad optical fiber

A new design of the silica-air double-clad optical fiber is proposed. The fiber was prepared from an MCVD preform inserted into a supporting silica tube with a fluorine-doped connective element with a lower refractive index (Δn~-4×10^-3) and air as the second cladding. A numerical aperture as high as 0.3 was measured for the first cladding and for fiber lengths up to 50 cm. Although it is realized that the results are preliminary, the optimization of the fiber parameters promises a new all-glass design for double-clad optical fibers for high-power fiber laser applications     

Coherence and intersymbol interference in digital fiber optic communication systems

Because of the quadratic relation between optical power and optical field, the transmission of optical power through an optical fiber is, in principle, nonlinear. Under usual conditions, random fluctuations of the incoherent source field and mode mixing tend to linearize the system. Previous assessments of the effect of intersymbol interference (ISI) on the performance of digital fiber optical communication systems are based on the assumption of linearity. This paper examines the effect of ISI on error rates in the other limit of complete coherence where fields are additive but powers are not. It is found that in this nonlinear regime and for weak dispersion, ISI may reduce the error rates slightly, whereas strong dispersion augments it considerably.     

Increase of the SBS threshold in a short highly nonlinear fiber byapplying a temperature distribution

We evaluate numerically and experimentally the stimulated Brillouin scattering (SBS) threshold increase for a short, highly nonlinear GeO₂-doped fiber by applying different temperature distributions along the fiber. The temperature coefficient for the Brillouin frequency downshift is measured to 1.2 MHz/°C. A threefold SBS threshold increase is obtained for a 100-m long highly nonlinear fiber with a 140°C temperature gradient. The proposed scheme is implemented in a wavelength converter based on fiber optical four-wave mixing (FWM). The SBS suppression scheme shows negligible influence on the FWM efficiency as well as the wavelength conversion bandwidth. The temperature coefficient for the zero dispersion wavelength is measured to 0.062 nm/°C     

Improvement of dispersion resistance in analog radio-on-fiber upconversion links

Dispersion fiber sensitivity in optical microwave upconversion links is investigated. Simulations are carried out to calculate output optical spectra and to evaluate mixing power as a function of fiber length for different upconversion systems using dual drive/standard Mach-Zehnder modulators or an unbalanced Mach-Zehnder interferometer (UMZ). The latter solution prevents complete cancellation of mixing power because of the asymmetric double sideband optical spectrum detected at the output of the UMZ. It is shown that an optimum value of the linewidth enhancement factor of the laser diode can be found to minimize degradations of the mixing power along the fiber.     

Fabrication of single-mode chalcogenide optical fiber

Long lengths (>150 m) of single-mode chalcogenide optical fiber were fabricated by a double crucible technique. Single-mode transmission through 10 m of continuous fiber was demonstrated using an F-center laser at 2.7 μm. The optical loss of this fiber was measured by a standard cutback technique using an FTIR spectrometer and also using an F-center laser, A minimum loss of less than 1 dB/m was obtained     

Monomode-Fasersensor zur ortsaufgelösten Temperatur-bzw. Dehnungsmessung basierend auf der stimulierten Brillouin-Streuung

A fiber sensor is described based on stimulated Brillouin-scattering for distributed temperature or strain measurements using single-mode fibers with lengths exceeding 20 km. A sinusoidal intensity modulated optical signal is used as a probe (frequency domain analysis). Experiments have been carried out at λ=1.32 μm and it is demonstrated that a spatial resolution of 1 m has been achieved using fibers of 1 km and 11 km length with resolutions in temperature of 2.6°C and in strain 0.006%.     

Drawing of optical fiber with internal codrawn wire and conductive coating and electrooptic modulation demonstration

One hundred twenty meters of fiber with an internal codrawn wire and electrically conductive coating was successfully fabricated for the first time. The integration of the conductive coating and wire was all performed during the fiber draw stage, in a process that enabled arbitrarily long lengths of fiber to be made. The wire combined with the conductive coating enables a strong electric field to be formed across the optical core. Such a fiber is ideal for thermally poling long lengths and for nonlinear device applications such as optical switches and modulators.